PROJECT SUMMARY From Vinblastine to Morphine, alkaloid natural products have contributed enormously to the treatment of human health and their impact has touched nearly every area of disease biology. Despite past successes, the number of new FDA-approved medicines derived from, or inspired by, complex alkaloids are waning. The multifarious and not-easily-manipulated chemical structures of intricate alkaloids, combined with complex, and often unknown, cellular target profiles has contributed to the abandonment of many natural product-based drug discovery programs. High-throughput screening approaches now dominate the hit-to-lead process. Yet there is growing concern over the lack of diverse three-dimensional complexity in many screening libraries, and natural products, and their derivatives, are recognized as filling an important area in bioactive compound space. This proposal seeks to address such limitation through both advances in synthetic chemistry pathways as well as cutting-edge chemoproteomics platforms to map the protein targets of a variety of judiciously chosen alkaloid natural products. The targets selected for this program represent both state of the art challenges for efficient complex molecule synthesis as well as scaffolds ideal for further medicinal chemistry discovery. Despite their small size, and potential to treat a variety of diseases, members of the altemicidin alkaloids require roughly thirty steps to prepare. The need to prepare new antibiotics is critical and many successful antibiotic classes have been derived from natural products, often ones with one or more nitrogen atom. The curvulamine alkaloids represent a promising new antibiotic class with reported activity against both gram negative and positive pathogens and possess a completely novel chemical structure. Finally, covalently acting alkaloids derived from tyrosine show potent anti-cancer effects yet their biological targets are unknown. Overall this work will utilize innovative synthetic chemistry approaches to synthesize complex alkaloid natural products and their derivatives in an efficient manner and with unprecedented structural diversity for further biological evaluation. Using cutting-edge chemoproteomics platforms, we will determine the cellular targets responsible for a given phenotype. In the process of carrying out this work, students and post-docs will be provided with rigorous and intellectually stimulating training in synthetic chemistry and chemical biology and will be well prepared for careers in biomedical research and drug discovery.